【openfire插件开发】群组聊天中的中介者模式

原文链接：http://www.hechunchen.info/?p=54

 

生活中的中介者非常常见，比如维护世界和平的联合国组织、房屋中介、出国中介。那么，设计模式中的中介者模式是怎么样的呢？我们openfire中的群组聊天就是a typical example。我们用一个简化的群组聊天模型来说明mediator（中介者）模式。  

我们的考虑是这样的，我们在用户之间添加中介者——聊天室。这样的话，用户之间的耦合度就会降低，而且不需要相互引用。它们只需独立地跟中介者交互即可。 结构图如下：

下面贴上关键代码。 接口IChatroom.java：

package mediator;

public interface IChatroom

{

    void forward(User from, User to, String message);

}

 

Chatroom.java:

package mediator;

public class Chatroom implements IChatroom

{

    @Override

    public void forward(User from, User to, String message)

    {

        // TODO Auto-generated method stub

        if(to!=null)

        {

            to.receive(from, message);

        }

    }

}

 

抽象类User.java:

package mediator;

public abstract class User

{

    IChatroom room;

    public User(IChatroom room)

    {

        this.room = room;

    }

    public abstract void send(User to, String message);

    public abstract void receive(User from, String message);

}

 

MaleUser.java:

package mediator;

public class MaleUser extends User

{

    public MaleUser(IChatroom room)

    {

        super(room);

        // TODO Auto-generated constructor stub

    }

    @Override

    public void receive(User from, String message)

    {

        // TODO Auto-generated method stub

        System.out.println("帅哥我收到了：" + message);

    }

    @Override

    public void send(User to, String message)

    {

        // TODO Auto-generated method stub

        room.forward(this, to, message);

    }

}

 

FemaleUser.java:

package mediator;

public class FemaleUser extends User

{

    public FemaleUser(IChatroom room)

    {

        super(room);

        // TODO Auto-generated constructor stub

    }

    @Override

    public void receive(User from, String message)

    {

        // TODO Auto-generated method stub

        System.out.println("美女我收到了：" + message);

    }

    @Override

    public void send(User to, String message)

    {

        // TODO Auto-generated method stub

        room.forward(this, to, message);

    }

}

 

测试类TestClient.java:

package mediator;

public class TestClient

{

    /**

     * @param args

     */

    public static void main(String[] args)

    {

        // TODO Auto-generated method stub

        IChatroom room = new Chatroom();

        FemaleUser hcc = new FemaleUser(room);

        MaleUser fq = new MaleUser(room);

        MaleUser gq = new MaleUser(room);

        MaleUser lp = new MaleUser(room);

        //男给男发消息

        gq.send(fq, "吃饭了没?");

        //男给女发消息

        lp.send(hcc, "我也没吃饭");

    }

}

 

总结一下，Mediator改变了原来两个对象的耦合方式。